1. Field of the Invention
The present invention relates to a gas feeding nozzle for a normal pressure chemical vapor deposition apparatus.
There have so far been known a physical vapor deposition process, a chemical vapor deposition process, a spraying process, a dipping process and so on as methods of forming a thin film on the surface of a substrate such as glass, metal, and the other various materials. These techniques have been selected depending on conditions such as the material or the thickness of film required for manufacturing. Especially, the physical vapor deposition process and the chemical vapor deposition process have been generally employed as methods capable of forming a film having a thickness of about several 100 .ANG. to several 10,000 .ANG. in a uniform manner and having a desired composition. Particularly, for the demand of use of a large-sized substrate and for high processability in industrial scale, a normal pressure chemical vapor deposition process (hereinbelow, referred to as a normal pressure CVD process) is used as an advantageous technique.
When large-sized substrates are produced by the normal pressure CVD process in industrial scale, the substrates are carried into a CVD chamber which is provided with a carrying means such as a belt conveyor or rollers to continuously carrying the substrates into the chamber and a nozzle having a wide width for feeding a reactive gas, the CVD chamber having a predetermined temperature profile, and a thin film is formed on the substrates by supplying the reactive gas from the nozzle.
Heretofore, it has been difficult to form the thin film having a uniform thickness of the large-sized substrates by the above-mentioned method. For instance, when a thin film of electric conductive tin oxide is to be formed on glass substrate having a width of 300 m/m, the scattering of the film thickness on the substrate in its width direction is at most about .+-.10%.